<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>测试for...in循环案例</title>
</head>

<body>

    <p>点击下面的按钮，循环遍历对象 "person" 的属性。</p>
    <button onclick="myFunction()">点击这里</button>
    <p id="demo"></p>
    <script>
        function myFunction() {
            var x;
            var txt = "";
            var person = {
                fname: "Bill",
                lname: "Gates",
                age: 56
            };
            for (x in person) {
                txt = txt + person[x];
            }
            document.getElementById("demo").innerHTML = txt;
        }
    </script>

</body>

</html>